1. Field of the Invention
The present invention relates to an illumination display switching device, and more particularly, to an illumination display switching device that improves visibility by illuminating from a backside a display design part such as letter, symbol or figure, which is formed on a switch knob for operating a push button-type switch.
2. Description of the Related Art
As an example of the illumination display switching device, an illumination display switching device is known which is used for an operation switch of an air conditioner device, an audio device and the like of a vehicle (refer to JP-A-2008-192407). That is, a switch knob that is supported to be slidable in an operation direction of the switch and a push bar that protrudes from a backside of the switch knob are integrally molded with a transparent resin material, a leading end of the push bar is formed with being contacted to an operation part of a push button-type switch and the switch knob is pushed to operate the push button-type switch. Also, in order to form a display part for identifying a type and the like of the switch such as letter, symbol, figure and the like on an operation surface of the switch knob, a part except for the display part is colored with a light-blocking paint so that only the display part is illuminated.
In particular, according to JP-A-2008-192407, the push button-type switch has a hollow cylindrical shape, a light emitting diode (LED) is accommodated in the cylinder to thus form a switch part on a cylindrical wall and an axis of the push bar operating the push button-type switch and molded with the transparent resin is matched with a center of the LED. Thereby, since a center of the operation of the switch knob and a central axis of the push button-type switch can be matched, a feeling (operation feeling) of the switch knob can be improved. Also, although a diameter of a part of the push bar, which is light-coupled to the LED, is small, a part that is connected to the display part of the switch knob is formed to have a cone-shaped enlarged part and an outer surface of the push bar is painted so as to suppress the internal light from leaking to the outside, thereby improving illumination performance of the display part.
As another example of the illumination display switching device, JP-A-2000-173379 discloses that a cylindrical switch knob, which is supported to a cylindrical attachment member to be slidable in an operation direction of a switch, is arranged above a push button-type switch and a light source. The switch knob has a disc-shaped upper part having a display part that is formed at an upper end of a hollow cylinder of the switch knob and is made of at least a light-transmitting material. A light-blocking member is provided at a part except for the display part of the switch knob, so that only the display part is illuminated to thereby improve the visibility. Meanwhile, the hollow cylinder of the switch knob is provided with a cylindrical light guide member inserted therein, which guides the light of the light source arranged just below the switch knob to the display part. Also, a lower end of the hollow cylinder of the switch knob is formed at a part thereof with a protruding push part that operates the push button-type switch. Also, a spring that pushes up and maintains the switch knob is provided to abut on the lower end of the hollow cylinder.